ATC Code N05BB01, R06AX33
Formula C21H27CIN2O2
Molar Mass (g·mol−1) 374,904
Physical State solid
Melting Point (°C) 200
Boiling Point (°C) 220
PKS Value 2,47
CAS Number 68-88-2
PUB Number 3658
Drugbank ID DB00557
Solubility soluble in water


Hydroxycin is an antihistamine that, in addition to treating allergic conditions (chronic itching and hives), is also used to relieve anxiety and tension, as well as sleep and sleep disorders.
Im Handel ist Hydroxycin in Tablettenform oder als Sirup erhältlich.



The antihistamine and antiallergic effects are based on the blocking of the H1 histamine receptor by hydroxycin and its active attenuation of activity.
Durch die Beeinflussung von Botenstoffsystemen im Gehirn wirkt das Arzneimittel auch beruhigend, sedierend und krampflösend.
Die Wirkung von Hydroxycin tritt innerhalb von 15 bis 60 Minuten ein und hält bis zu 6 Stunden an.


After oral administration, hydroxycin is rapidly absorbed from the gastrointestinal tract and reaches maximum plasma concentration after approximately 2 hours. The drug is metabolized in the liver by the CYP3A4 and CYP3A5 enzymes. 70% of the active intermediate hydroxyzine is excreted in the urine. The half-life in children, adults, and the elderly is approximately 7, 20, and 29 hours, respectively.


Hydroxycin should not be taken in case of:

  • Hypersensitivity
  • severe liver or kidney failure
  • Prostate enlargement
  • Narrow-angle glaucoma
  • Porphyrias
  • pregnancy and breastfeeding

Drug interactions

Interactions with alcohol, central depressant drugs, MAO inhibitors, parasympathomimetics and antihypertensives are possible with concomitant use, as well as with betahistine, epinephrine, phenytoin and cimetidine.


Side effects

Drowsiness, dullness, headache, and dry mouth are common with the use of hydroxycin.

Toxicological data

Severe sedation is most common with overdose, but convulsions, drowsiness, nausea, or vomiting often occur.
LD50 (Ratte, oral): 840 mg/kg
LD50 (Maus, oral): 400 mg/kg

Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter ist Autor zu pharmazeutischen Themen in der Medizin-Redaktion von Medikamio. Er befindet sich im letzten Semester seines Pharmaziestudiums an der Universität Wien und liebt das wissenschaftliche Arbeiten im Bereich der Naturwissenschaften.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer ist seit 2020 freie Autorin bei Medikamio und studierte Pharmazie an der Universität Wien. Sie arbeitet als Apothekerin in Wien und ihre Leidenschaft sind pflanzliche Arzneimittel und deren Wirkung.

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